In slurry or bulk phase polymerization processes the effluent slurry from the reactor is normally freed of solvent or liquid monomer, the catalyst killed, the product purified and recovered as a powder which is then extruded and chopped into pellets. This is an expensive process having a large vent loss of monomers which must be purified for reuse and the solvent in slurry polymerization must be purified to remove catalyst deactivants, etc. Further, the process is energy intensive in that large extruders are normally employed. Vapor phase polymerization can be less expensive and, recently, important improvements in the economics of vapor phase polymerization of monomers have been claimed for new processes taught in U.S. Pat. No. 3,970,611 and U.S. Pat. Appl. No. 642,583, filed Dec. 12, 1975.
Now a way has been found to utilize many of such improvements in slurry polymerization to form processes in which polymerization is continued after the slurry is removed from the reactor so that the heat of further polymerization can be used to dry the particulate and, optionally, convert it to a transferable melt which can be handled as a viscous liquid instead of as a powder so that expensive extrusion equipment is not needed; moreover, the flashed polymerization medium can be recondensed and recycled without extensive purification.